Screenshot of vlc in overlay mode (while playing a video) shows a black rectangle

Description

a) open vlc to play an internet tv station stream.
b) while vlc is playing the video,
press "print screen" key to take a screenshot,
c) open the screenshot-image with ShowImage,
vlc window has a black rectangle.

more:
start vlc again, open a video,
or let vlc plays the previous video;
move litle by litle the ShowImage window
(with contains the screenshot with the
black vlc window, in front of vlc, surprise!
in the black vlc window of the ShowImage,
you see the video that vlc plays in the
background.

note: vlc doesn't have this behavior on hrev5,
so i guess it is not vlc bug.

first i must make a correction (examine more closely the ticket):
hrev5 has exactly the same behavior.
the window in the screenshot is not black but gray
(so the note on the description is not correct), i still
don't know how this came out to my mind:)

That's normal, since the screenshot is taken from the frame buffer, while the actual bitmap data that's shown in overlay mode never actually hits that (the bitmaps being drawn/scaled into that are reside directly in the graphics card's VRAM). It'd take quite some hacks to get that to take a screenshot properly in such a case.